Units – Debye as a measure of electric dipole moment Electric dipole moment is often reported in Debye (D). Choose the correct SI-equivalent for 1 Debye.
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A3.33 × 10^-30 C·m
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B3.33 × 10^-30 C·m^2
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C3.30 × 10^-10 C·m
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D3.33 × 10^-10 C·m^2
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E3.33 × 10^-28 C·m
Answer
Correct Answer: 3.33 × 10^-30 C·m
Explanation
Introduction:The Debye (D) is a convenient unit for molecular-scale dipole moments used in chemistry, materials science, and dielectrics. Converting Debye to SI units (C·m) helps compare theoretical predictions and experimental measurements consistently.
Given Data / Assumptions:
- Definition of dipole moment p as charge × separation.
- Standard conversion constants between cgs electrostatic and SI units.
Concept / Approach:
By definition, 1 Debye ≈ 3.335 64 × 10^-30 C·m. For most engineering calculations, 3.33 × 10^-30 C·m is used as a rounded value. This small magnitude reflects molecular-scale separations and elementary charges in polar molecules.
Step-by-Step Solution:
Recall definition: 1 D = 10^-18 esu·cm.Convert to SI: 1 esu of charge ≈ 3.335 64 × 10^-10 C.Hence 1 D = 3.335 64 × 10^-30 C·m ≈ 3.33 × 10^-30 C·m.Verification / Alternative check:
Typical water dipole moment ≈ 1.85 D translates to ≈ 6.17 × 10^-30 C·m, consistent with literature values.
Why Other Options Are Wrong:
Options with m^2 have wrong dimensions; 10^-10 C·m is orders of magnitude too large; 10^-28 C·m is also incorrect.
Common Pitfalls:
Mixing up cgs and SI, or confusing Debye with Coulomb-meter-squared.
Final Answer:
3.33 × 10^-30 C·m